In the present description, the term connection cables is intended as indicating cables, electric cables in particular, fitted with connection means at one or both ends, electrical connections in particular, and with at least one of the two ends fitted with a portion in a thermoplastic material obtained by overmoulding the end itself. In the following description, for simplicity of exposition, reference will only be made to electric cables.
The term overmoulding is intended as the process that provides to place an end of the cable, in general fitted with means of electrical connection, inside an injection mould and to inject thermoplastic material into the mould to cover part of the means of connection in correspondence to said end, in order to allow them to be used safely or to make geometric shapes for fastening them, as in a cable gland for example.
For example, in the manufacture of a plug on electric cables the metal elements that constitute the contacts of the plug and form the insert are connected to the electrical wires of the cable and then overmoulded with a thermoplastic material that allows the insert to be kept in the desired position and gives the plug its external shape and final functionality.
In particular, the apparatus according to the present invention relates to the moulding of connectors, plugs and similar elements over the ends of electric cables.
The invention also relates to a particular injection moulding press suitable for overmoulding connection cable ends as defined above.
There are apparatuses known in the art for manufacturing the ends of electric cables that envisage means for fastening electrical connection portions to the ends of the cables and injection presses for overmoulding one or both ends of the cable. These presses are provided with a mould equipped with a plurality of cavities, or impressions, in which the ends of a corresponding plurality of cables are inserted for injection over moulding. In other words, apparatuses in conventional systems have large moulds with a high number of impressions, where a corresponding number of ends of electric cables fitted with electrical connection elements are inserted. The thermoplastic material is injected over these ends to form, for example, a plug or a socket.
On these presses, the end of the cable to be processed is usually inserted by hand and, after injection of the material and its solidification, the removal of cables from the mould and testing of the overmoulded cables are also carried out manually, to the detriment of speed and efficiency in the production process.
Apparatuses are also known wherein the loading of the cable heads to overmould and the discharge of the overmoulded cables is carried out automatically, but said apparatuses still do not allow all tests on the finished product to be carried out during the manufacturing steps, to the detriment of the product quality.
The testing step consists in checking that the end of the cable has not moved during the pressurized injection of the thermoplastic material into the mould with consequent emergence of the insert, or part of the cable, from the solidified thermoplastic material. The movement of the insert or the cable itself inside the mould can also cause the total or partial loss of the connection between the conductor wires inside the cable and the overmoulded connection element, making it useless; for this reason, an electrical test is also carried out on the cable, putting it in similar conditions to those of carrying current when powering a domestic appliance, to check its correct operation.
This is carried out by connecting both ends of the cable's individual conductors to a current generator to check if the electrical circuit closes and so confirm the functionality of the cable and the connectors and/or plugs and sockets that have been overmoulded on its ends.
A drawback of known apparatuses is the impossibility of performing this test automatically and without interrupting the production cycle.
A further drawback of known apparatuses is the great difficulty or substantial impossibility of processing the two cable ends together: in fact, in said apparatuses, because of balancing and correct filling requirements of the mould shapes, as a rule it is not possible to inject the same material in cavities having mutually different sizes and geometry. In this case, it is necessary to first mould the first end of the cables and afterwards, by means of a second mould, moulding the second end.